Broken forearm update and queries. Case?

I am a 16 year old male. I had a displaced both-bone forearm fracture that was reduced and placed in a plaster cast about a week ago. My follow-up X-ray was checked by the doctor, who said the alignment is fine, with only a little bending. For the last ~2 days after the follow up session, I have had significant tightness and stiffness feeling around my wrist, especially on one side, which feels different from before. When I bend/open my fingers, particularly the little finger, I feel some pain/tightness around the wrist. I also occasionally get brief burning/hot-water-like or nerve-type sensations and a heartbeat/pulsing feeling around my elbow . My fingers are warm, normally coloured and movable, and I do not have constant or severe pain. Could this be swelling, nerve/tendon irritation, or pressure from the cast, and should the cast be checked or adjusted? Also, given my age and isolated arm fracture, is there any need for a blood thinner, or is it unnecessary in my case?